At present, such services are accessible from a mobile terminal connected to mobile telecommunications networks such as General Packet Radio Service (GPRS) and Universal Mobile Telecommunications system (UMTS) networks.
At present, in such mobile networks, the user can select a communications network offering services by selecting a name identifying that communications network. To set up a connection between a mobile terminal and a particular communications network, that name is sent over the mobile network to an equipment managing access to the communications networks.
To facilitate the explanation of the invention, the description uses GPRS and UMTS terminology. However, the invention applies to all communications systems using identical techniques for identifying and addressing a communications network.
In existing systems of the GPRS and UMTS types, the name identifying a communications network is called its access point name (APN). In these systems, the equipment supporting services is known as a Serving GPRS Support Node (SGSN) and the equipment managing access to the communications networks is called the Gateway GPRS Service Node (GGSN).
An APN primarily comprises an identifier of the selected communications network, an identifier of the operator managing that communications network, and an identifier of the mobile network technology, for example the GPRS or UMTS technology. The format and use of access point names APN are covered by standards issued by the European Telecommunications Standards Institute (ETSI).
One function of an SGSN is to receive an APN from a mobile terminal and to forward it for recognition to the APN server to which it is connected. That APN server responds to the SGSN by sending a list of the GGSN associated with the APN. The SGSN sets up a connection to a GGSN from this list. One function of a GGSN is to recognize an APN received from a mobile terminal and to set up a connection to a communications network corresponding to that APN. The SGSN and the GGSN are also covered by standards issued by the ETSI.
Once an APN has been selected on the mobile terminal, an access protocol is started. In the case of the GPRS or the UMTS, this protocol is the Packet Data Protocol (PDP). A procedure for setting up a connection from the mobile terminal to the GGSN is executed. To enable the connection to be set up, a link to the selected communications network is created via the mobile network. In the case of the GPRS or the UMTS, this link is called a PDP context link. It provides access from the mobile terminal to all the services of the communications network.
On completion of the above procedure, the terminal receives from the communications network with which a connection has been set up an address that identifies the terminal within that communications network. It is associated with the PDP context link between the terminal and the communications network.
By analogy with fixed network telephony and Global System for Mobile communications (GSM) systems, the connection request from a mobile terminal to a communications network is referred to as an outgoing call request.
Similarly, a connection request from a communications network to a mobile terminal is referred to as an incoming call request.
At present, GPRS and UMTS mobile telecommunications network operators do not allow a connection to be set up from the communications network to the mobile terminal.
At present a connection between a mobile terminal and a communications network can be established only from the mobile terminal to the communications network.